1. Field of the Invention
The invention relates to a system for actuating a member and methods of using the system to actuate the member. The invention also relates to using the system for actuating a device to meter fuel in a heat engine, such as, for example, an aeronautical turbine engine.
2. Description of Related Art
It is known to use an actuating system comprising an electric motor, for example, a stepping-type electric motor, which includes a device for transmitting the movement of the electric motor to a valve that supplies fuel to the heat engine. The electric motor is controlled by a computer that is configured to regulate the current supplied to the electric motor as a function of a setpoint position of the valve. The setpoint position is derived from an acceleration command initiated by the pilot of the plane having the heat engine, to supply a desired amount of fuel to the heat engine.
It has been proposed to make such actuation safer by comparing the actual movement of the electric motor with a movement corresponding, theoretically, to the applied setpoint, to detect, in real time, any anomaly in the actuation.
To accomplish such, it has been proposed to measure the actual movement of the electric motor using a resolver-type sensor, which delivers information about the absolute angle of the rotor of the electric motor in the form of analog signals.
The integration of a resolver-type sensor in an actuating system poses many problems. For example, resolver-type sensors are particularly bulky and relatively heavy due to the technology used to provide the sensors, which requires a rotor and a stator that may have a number of wire windings wound around a metal core.
Moreover, the volume needed to integrate the resolver-type sensors often requires the sensors be mounted on a rotor parallel to the electric motor. Consequently, particularly in the case of small actuating systems, the sensor becomes a bulky component of the electric motor and significantly contributes to the total mass of the actuating system.
Furthermore, since the position information delivered by the resolver-type sensor is analog in nature, the actuating system must include an analog/digital conversion stage at the input of the computer to make use of the position information.
Moreover, particularly in the context of the use under consideration, it is indispensable to obtain reliable and precise actuation, and to do so under use conditions that are severe in terms of vibrations, temperatures and pressures.
Resolver-type sensors do not optimally satisfy the constraints, particularly in terms of reliability, due to the large number of elements of which they are composed and the presence of an additional analog/digital conversion stage within the computer.
The same is true of resistive-type sensors, the reliability of which is highly affected by severe use conditions.